Japan’s military thwarted a declaration of war on the United States before Pearl Harbor, said former Japanese Ambassador Takeo Iguchi at a talk sponsored by the Center for National Security Law September 22.

Iguchi, an accomplished diplomat and scholar who is now professor emeritus at Shobi University in Tokyo, has devoted the past 10 years researching a point in history he believes has been grossly misrepresented by many modern historians.

While common belief—both inside and outside academic circles—holds the United States partly responsible for its lack of preparation and foresight before the attack, Iguchi faults the Japanese for failing to follow expected diplomatic procedures for declaring war.

“Study on Pearl Harbor diplomacy has been neglected, to my surprise, for half a century,” Iguchi said. He called for a “reinvestigation, a reappraisal, a search of original materials.”

His own reinvestigation was shaped largely by the discovery of official documents in 1999 that, he said, clearly indicate Japan did not comply with international law, stipulating “a prior delivery of ultimatum in clear wording to bring about a state of war which ipso facto terminates diplomatic relations.”

Iguchi pointed out that Japan did follow the necessary protocol when entering World War I. The former ambassador found that in World War II, however, the Foreign Ministry did not send the United States what constituted an ultimatum. What was to pass for an ultimatum was Japan’s Final Memorandum to the United States, a message that did not include any specific wording regarding the use of armed forces. Furthermore, while the message was meant to be sent a half hour before the attack on Pearl Harbor, a tangled-up delay resulted in the memorandum not actually being delivered until 20 minutes after the attack had already occurred. Iguchi’s studies have delved into the mystery surrounding this delay.

The reason for the lapse, Iguchi found, is that the Japanese military “thwarted” the Ministry’s initial plans to abide by set procedure. The military was against “any clear-cut announcement of force,” Iguchi said, “since it might jeopardize their military plan for a successful operation.”

It was only through the exploration of previously undisclosed documents that Iguchi could reach such conclusions. In 1998 Iguchi uncovered a particularly telling document, called “Confidential War Diary,” which Iguchi noted has not been published by any military historians despite its immense historical value. Inside, a member of the Imperial Headquarters’ Army General Staff had written on Dec. 2, 1941, “The U.S. is not yet aware of Japan’s true intent. Success of surprise attack is not to be doubted.”

Iguchi said he has brought his findings to the United States to open the issue to American scholarship. Although he has garnered some support at home, including that of three ambassadors and one major newspaper, many more Japanese academics, administrators, and citizens dispute his conclusions.

Iguchi stands firmly grounded in his research, however. He hopes to stimulate broader international study of Pearl Harbor diplomacy in an effort to bring the true story to light and support the work of “sincere historians” in Japan.